Semiconductor device manufacturing method thereof

Abstract

Cutting work is performed on an n-semiconductor substrate ( 1 ) with an inverted trapezoid-shaped dicing blade to form grooves to be a second side walls ( 7 ). Bottom portions of the grooves are contacted with a p-diffusion layer ( 4 ) which is formed on a first principal plane ( 2 ) (front face) of the n-semiconductor substrate ( 1 ), so that the p-diffusion layer ( 4 ) is not cut. Then in the second side walls ( 7 ), a p-isolation layer ( 9 ) connected to a p-collector layer ( 8 ) and the p-diffusion layer ( 4 ) is formed. Since the p-diffusion layer ( 4 ) is not cut, a glass support substrate for supporting a wafer, and expensive adhesive, are not required, and therefore the p-isolation layer ( 4 ) can be formed at low cost.

The invention claimed is: 
     
       1. A method for manufacturing a semiconductor device, comprising the steps of:
 forming a second conductive type first region on a surface layer of a first principal plane of a wafer and in an outer periphery portion of a semiconductor device formed on the wafer; 
 forming grooves which reach the first region with a dicing blade from a second principal plane to the first principal plane of the wafer; 
 removing processing strain formed on the grooves by etching; 
 forming a second conductive type isolation layer on a surface layer of the grooves and a second conductive type collector layer on a surface layer of the second principal plane so that the isolation layer and the collector layer are connected; 
 forming a collector electrode on the collector layer; and 
 cutting into chips the wafer in the first region sandwiched between the first principal plane and each bottom portion of the grooves approximately vertically with respect to the first principal plane by dicing or by laser. 
 
     
     
       2. The method for manufacturing a semiconductor device according to  claim 1 , characterized in that a depth of the first region is 30 μm or more and 170 μm or less. 
     
     
       3. The method for manufacturing a semiconductor device according to  claim 1  or  claim 2 , characterized in that a distance between the bottom portions of the grooves and the first principal plane is 10 μm or more and 150 μm or less. 
     
     
       4. The method for manufacturing a semiconductor device according to  claim 1 , characterized in that a shape of the dicing blade for forming the grooves is a V shape, inverted trapezoid shape or U shape. 
     
     
       5. The method for manufacturing a semiconductor device according to  claim 1 , characterized in that the collector electrode is extended toward an inner wall of the grooves. 
     
     
       6. The method for manufacturing a semiconductor device according to  claim 1 , characterized in that a depth of the processing strain of the grooves is 1 μm or more and 20 μm or less. 
     
     
       7. The method for manufacturing a semiconductor device according to  claim 1 , characterized in that a depth, when removing the processing strain of the grooves by etching, is 3 μm or more and 50 μm or less. 
     
     
       8. The method for manufacturing a semiconductor device according to  claim 1  or  claim 7 , characterized in that the etching is performed by acid etching or dry etching. 
     
     
       9. The method for manufacturing a semiconductor device according to  claim 1 , characterized in that a depth of the grooves in an outer periphery portion of the wafer away from a region to be the chips is shallower than a depth of the grooves in the region to be the chips. 
     
     
       10. The method for manufacturing a semiconductor device according to  claim 1 , characterized in that at least a part of the grooves do not reach an outer edge of the wafer in an outer periphery portion of the wafer away from a region to be the chips. 
     
     
       11. The method for manufacturing a semiconductor device according to  claim 1 , characterized in that the isolation layer and the collector layer are simultaneously formed by performing ion implantation and thermal processing on side faces of the grooves formed with the dicing blade and the second principal plane. 
     
     
       12. A method for manufacturing a semiconductor device, comprising the steps of:
 forming a second conducive type first region on a surface layer of a first principal plane of a wafer and in an outer periphery portion of a semiconductor device formed on the wafer; 
 forming a composite mask by forming an aluminium film and a negative resist film in this sequence on a second principal plane of the wafer and performing patterning; 
 performing dry etching using the composite mask as an etching mask and forming grooves reaching the first region so that a groove width widens from a bottom portion to an opening portion; 
 selectively removing the negative resist film; 
 implanting second conductive type impurity ions into the second principal plane under the aluminum film and side faces of the grooves; 
 irradiating a first laser beam onto an entire surface on a side of the second principal plane of the wafer under relatively high energy conditions, which are appropriate for activating the impurity ions implanted into the side faces of the grooves, in a state of the aluminum film remaining in the second principal plane of the wafer, and forming a second conductive type isolation layer on a surface layer of the side faces of the grooves; 
 removing the aluminum film and exposing the second principal plane; 
 irradiating a second laser beam onto the entire surface on a side of the second principal plane of the wafer under relatively low energy conditions, which are appropriate for activating the impurity ions implanted into the second principal plane, and forming a second conductive type collector layer on a surface layer of the second principal plane so that the isolation layer and the collector layer are connected; 
 forming a collector electrode on the collector layer; and 
 cutting into chips the wafer in the first region sandwiched between the first principal plane and each bottom portion of the grooves approximately vertically with respect to the first principal plane by dicing or by a laser beam. 
 
     
     
       13. The method for manufacturing a semiconductor device according to  claim 12 , characterized in that the aluminum film is formed to have a thickness thicker than 0.05 μm and thinner than 1 μm. 
     
     
       14. A method for manufacturing a semiconductor device, comprising the steps of:
 forming a second conductive type first region on a surface layer of a first principal plane of a wafer and in an outer periphery portion of a semiconductor device formed on the wafer; 
 forming an aluminum film on a second principal plane of the wafer; 
 forming grooves reaching the first region from the second principal plane to the first principal plane of the wafer with a dicing blade so that a groove width widens from a bottom portion to an opening portion; 
 implanting second conductive type impurity ions into the second principal plane under the aluminum film and side faces of the grooves; 
 irradiating a first laser beam onto an entire surface on a side of the second principal plane of the wafer under relatively high energy conditions, which are appropriate for activating the impurity ions implanted into the side faces of the grooves, in a state of the aluminum film remaining in the second principal plane of the wafer, and forming a second conductive type isolation layer on a surface layer of the side faces of the grooves; 
 removing the aluminum film and exposing the second principal plane; 
 irradiating a second laser beam onto the entire surface on a side of the second principal plane of the wafer under relatively low energy conditions, which are appropriate for activating the impurity ions implanted into the second principal plane, and forming a second conductive type collector layer on a surface layer of the second principal plane so that the isolation layer and the collector layer are connected; 
 forming a collector electrode on the collector layer; and 
 cutting into chips the wafer in the first region sandwiched between the first principal plane and each bottom portion of the grooves approximately vertically with respect to the first principal plane by dicing or by a laser beam. 
 
     
     
       15. The method for manufacturing a semiconductor device according to  claim 14 , further comprising a step of:
 removing processing strain, formed in the grooves due to the dicing blade, by etching in a state of the aluminum film remaining, after the grooves are formed with the dicing blade and before implanting the impurity ions. 
 
     
     
       16. The method for manufacturing a semiconductor device according to  claim 14 , characterized in that a cross-sectional shape of the dicing blade for forming the grooves is a V shape, or inverted trapezoid shape. 
     
     
       17. The method for manufacturing a semiconductor device according to any one of  claim 12  to  claim 16 , characterized in that the groove is formed so that an angle, formed by a line extending from the second principal plane where the opening portion is formed and the side face of the groove, is 40° or more and 85° or less on the opening portion of the groove.